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Controller
Hardware and Accessories Setup and Utility
Appendix 1: Cable Remote Terminal Units (CRTU)
an RTU’s connector actually disconnects the whole line downwards.
Discrete Inputs
Any component that closes/opens a dry contact can be used in discrete inputs. (For example: water
meters, fertilizer meters, pump fault contacts, etc.). The maximum measuring rate is 500mS (250mS
ON, 250mS OFF). When the communication rate to the controller is slower than the pulse rate, the
remote unit sums up all the pulses from one communication to the next communication, measures
the time between the last two pulses and transfers the data after processing to the controller, so that
the line’s communication rate and load do not effect the accuracy of measurement readings.
Analog Inputs
Sensors such as tension meters, anamometers or thermometers can only be connected to RTU
4-8-4 type remote units. The preferred standard is 0-10V, and care should be taken to maintain
low power consumption, for the reasons specified above. By changing the J1-J4 switch, the card
can also read sensors of 4-20mA standard, but for these sensors, power consumption is set by the
values measured and their effect on the entire line is significant. Connection of 4-20mA sensors will
severely limit the maximum number of units in the line, and in any case, no more than 8 sensors of
this type can be connected to a line, unless they are fed by an external power source.
Discrete Outputs
The discrete outputs were designed for operating latch solenoids and latch (pulse) type relays with
3 wires. The voltage is 12V DC and the pulse length is 50-80 mS. These solenoids are in fact
transducers that transform the pulse into a hydraulic command that open and close valves. Latch
relays translate the pulse into an elctric dry contact.
Adapter card
for Coordinating the Remote Unit with the Galileo Controller - C2000-15
The adapter card for linear remote units is a card that is inserted into one of the module
slots in the Galileo 2000 controller, and is accordingly defined as WireRTU. This card
includes a connector that is suitable for 3 wires, from which the cable goes out to the units.
Above the connector are two led lights that indicate the communication status. The upper
led lights up during communication and the lower led lights up during reception of input.
The communication rate on the three-wire line is 256 bps. Remote units whose inputs are
defined as connected to any device receive more attention and are scanned at a higher
rate than those that do not have connected inputs.
Remark:
Up to two C2000-15 cards can be installed in the Galileo 2000 controller. The
definition of the remote units begins with 1 in each line. CRTU adapter No. 2 (From the left
in the old models or from the top in the W model) will have the RTU number 65-128. e.g
definition of RTU no. 1 = no.65 for the controller and 64 = 128.
It should be noted that numerous RTUs create a heavy load on the controller’s processor.